When forming rigid plastics, such as polyvinyl chloride (PVC), by extruding, calendering or molding, the control of gloss is very important. Small changes in the forming temperature can greatly change the gloss of the surface of the article being produced. This is especially the case for extruded articles. The control of gloss is critical in applications such as house siding, where if different pieces of siding have different gloss levels, then the siding will not be as attractive on the house. Gloss levels can be lowered by reducing the extrusion temperatures. However, lower extrusion temperatures can result in poor physical properties if the resin has not properly fused. Also, low extrusion temperatures give rough surfaces on the extrudate.
To achieve a matte surface or to merely control gloss in extruded, calendered or molded rigid thermoplastics it is the accepted practice to add abrasive fillers to the composition. Abrasive fillers such as aluminum silicate, and large particle size calcium carbonate are added to the rigid compositions to give a matte surface. These abrasive fillers are detrimental to physical properties of the compositions and they are detrimental to the processing equipment. The abrasive fillers tend to cause excessive premature wear on extrusion equipment. These abrasive fillers are usually relatively large particles which are incompatible with the polymer network of the composition.
It would be desirable to have rigid thermoplastic compositions which could be formed into articles having a matte surface. It would also be desirable if the matte surface could be achieved without the use of abrasive fillers, and with an additive which is compatible with the polymer network of the composition. Good reproducibility of matte surface along with a broader latitude in processing temperature would also be highly desirable.